In many fields of engineering, notably aircraft manufacture, bundles of cables such as electric wires or fibre optic cables run in raceways. The raceways are generally open channels made of extruded aluminium. The bundles are retained in the channels at intervals by retainers locked into the channels. Often a raceway section has several parallel channels formed during a single extrusion, and it is important to ensure that the wires or cables are securely retained in their respective channels. If the wires and cables are not securely retain in their respective channels, they easily can become entangled with one another and become dislodged from their respective channels.
One conventional type of cable tie, known as a harpoon tie, is an elongated retainer, usually made of a plastics material, having at one end a small flat base beyond which a harpoon-like retention hook projects. The retention hoop has a resilient arrowhead which can be pushed through a corresponding aperture disposed at the bottom of the channel, the arrowhead having resilient barbs that engage the underside of the channel to hold the retainer in place with the flat base on the channel floor. The cable tie is positioned centrally within the channel, projecting upwards from the channel floor, and a wire harness is laid in the channel, the wires being separated 50:50 on each side of the tie and a retainer secured to the tie, typically by a latching arrangement.
The conventional harpoon cable tie is often time-consuming to install, as the ties need to be positioned about every 150 mm along the channel. It would be preferable to have a system that enabled wiring to be simply dropped in the channel as it is removed from its packaging, without the need to split it on either side of each tie, thereby saving time and reducing the risk of damage.
There is also a need for an improved method of removing the cable retainers from the harpoon ties and removing the harpoon ties themselves from their attachment to the raceway channel floor. The latter currently involves pressing inwardly the barbs on each harpoon tie to allow it, along with the fair lead and cable retainer, to be pulled out of the raceway in one operation. A specialty tool is conventionally required for this purpose, having a recess to engage the harpoon tie on the underside of the raceway, and, spaced from the recess, a fulcrum to engage part of the structure in which the raceway is mounted. The tool is rocked on the fulcrum to place the recess into engagement with the harpoon tie and compress the barbs inwardly as the tie is pulled out of the raceway from above. This involves great care to avoid damaging the wires retained by the tie.
Another conventional cable tie is shown in U.S. Pat. No. 4,993,669 ('669). In '669, the cable or bundle tie arrangement has a plastic tie strap and a tie head. The tie head includes a housing having a pair of spaced apart slots forming a pair of strap-receiving passageways. Each passageway has an entrance opening and at least one of them has an exit opening. A pawl-receiving channel extends through the housing along the passageway, the channel having at least one channel opening disposed substantially normal to the entrance openings where an intermediate portion of the channel intersects each of the passageways. A pawl member is mounted in the channel through the channel opening and includes a base portion and pair of arms extending from opposite sides of the base. Each of the arms has a free end with a blade section to engage an inner surface of a strap passing through one of the passageways. The strap can thus be pulled tight around a wire bundle and lockingly maintain the tension around the article or bundle being tied.